capAVI users / experts wanted

Since Windows OpenCV is based on Windows capAVI one would expect that there is some level of knowledge about it with OpenCV users. I have a different experience - most OpenCV "programmers" are on very high level - looking for "how to detect a license plate" using one line of code!
OK I am stretching it a little , but please - is there someone who knows how capPreview actually works, as an example?
Like to hear from you.